Abstract 224: Morphological characteristics of carotid webs associated with stroke risk and clot burden

Abstract

Introduction Carotid webs (CaWs) have been established as an ischemic stroke etiology although lesion characteristics that may lead to increased stroke risk are still uncertain (1). We aim to evaluate the associations between CaW morphological features evaluated via computed tomography angiography (CTA) with clinical and radiological variables. Methods This is a retrospective analysis of a prospectively collected mechanical thrombectomy database. Individuals that presented with a suspected symptomatic CaW since July 2014 were selected after appropriate workup. The database included symptomatic CaW, asymptomatic CaW contralateral to the symptomatic side in case of bilateral lesions, and incidentally identified CaW (asymptomatic patients). We recorded the following CaW variables (Figure 1): length, base, thickness, caudal/middle/cranial angles in relationship to the vessel axis, area as well as perimeter of the pocket. We used mixed‐effects models to compare measurements between symptomatic and asymptomatic webs in the complete sample and paired Wilcoxon tests to compare webs of individuals with contralateral, symptom‐discordant CaW. Measurements were evaluated against clot burden via Poisson regression.a Results 118 webs (85 symptomatic and 33 asymptomatic) from 98 stroke patients were included. Median [IQR] for age was 52[42‐58] years old, 69.0% were female, 68.4% presented with a single symptomatic web, 18.4% had both a symptomatic and an asymptomatic web, 11.2% had only an asymptomatic web, whereas 2.0% had bilaterally asymptomatic webs. Symptomatic CaW were significantly larger in length (2.5mm[2.1‐3.5] vs. 2.2mm[1.7‐2.7];p=0.004) and pocket area (1.5mm²[0.9‐2.6] vs. 0.9 mm²[0.2‐1.3];p=0.007) compared to the asymptomatic lesions. The cranial angle was more acute for symptomatic CaW (66.9°[57.1°‐78.4°] vs. 76.2°[66.9°‐88.7°];p=0.046). No other significant associations were noted. Among the 18 patients who were analyzed for contralateral/symptom‐discordant webs, symptomatic CaW also showed more extensive lengths (2.9mm[2.3‐4.0] vs. 2.2mm[1.6‐3.1];p=0.009) but less acute rostral angles (33.1°[25.3°‐43.5°] vs. 27.9°[16.8°‐35.9°]) than their asymptomatic counterparts. Among symptomatic webs, clot burden was not significantly associated with base, length, thickness, perimeter or pocket area. Nevertheless, each 15° increase in the angle within the pocket was associated with a 1.1‐fold increase in clot burden (exp(β) = 1.1(95%CI1.0‐1.2), p = 0.044) for each 15° increase), with more obtuse angles indicating a higher intracranial vessel occlusion thrombus load. Conclusion Symptomatic carotid webs displayed larger lengths and pocket areas as compared to asymptomatic lesions. The angles that determine pocket area and degree of stenosis differed between symptomatic and asymptomatic webs.